Method and apparatus for dispensing gas material



L. 1. DANA 1,950,353

METHOD AND APPARATUS FOR DISPENSING GAS MATERIAL Filed May 4, 1932 March 6,1934.

t/ IN\VIENTOR W ATTORNEYS n u 5 v Patented 6, 1934 UNITED STATES 6 Claims.

This invention relates to a method and appav ratus for dispensing gas material, particularly gas material-which is stored in the liquefied state at temperatures below 273 Kelvin, and has for 5 its principal'object to provide a method and :means for vaporizing adesired portion of lique- 1i iedtegllas, whereby an increase in pressure'is ef-' l means forincreasing the pressure of the gas material in the container by the vaporization of a portion of the liquefiedgas, in such a manner that undesired heating of the-main body of liquefled gas is avoided.

- g 5 A further object is to provide means for lengthening the period of elapsed time between the complete stopp e of withdrawal or discharge and the time when the pressure has reached a value at which the safety relief valve has been adjusted to open.

Other objects of the invention will in part be obvious and will in part appear hereinafter;

The invention accordingly comprises the several steps and the relation of one or more of such apparatus embodying features of construction, combinations ofelements and arrangement of parts which are adapted to effect such steps, all r as exemplified in the following detailed disclo- 30 sure, and the scope of the application of which willbeindicatedintheclaims. K

For a fuller understanding of the nature and to the following detailed description taken inconu nection with the accomp yi drawing in which:

The figure is a view, mainly in vertical section, illustrating a preferred form of container for liquefied gas together with cooperating apparatus 0 constructed in accordance with the invention.

Referring now to the drawing, a container of the insulated variety is depicted holding a body of liquefied gas in an'inner vessel 11. It also has an outer envelope 12, provided in spaced re- 45 lation about the inner vessel 11; the intervening space being substantially filled with a suitable insulating material 13, for example with magnesium carbonate, which permits heat leakage to the inner vessel only at a very low rate. I

Dispwed within the insulation is an auxiliary vessel 14 arranged to serve as a means for heating a portion of the liquefied gas at 10. In the preferred form shown, the-vessel 14 comprises a curved conduit disposed partly around and pref- Another object is to provide a method and g stem with respect to each of the otheraand the objects of the invention reference should be had a PATENT OFFICE.

METHOD AND APPARATUS FOR DISPENSING GAS MATERIAL A Application Mayid, 1932, Serial No. 809,122

provided at its upper end with a reduced portion 15 leading into the upper partof thevessel 11., At its lower portion thereis a connection 16 providing communication with the main body of liquid in the vessel 11, whereby liquefied gas may no flow out of the main vessel into the auxiliary ves- Sci 14 to seek its own level, forming a liquid column 17 adjacent to the main body of liquid. A conduit 18 for the passage of a heating agent is disposed within substantially the greater poras tion of the conduit 14; the conduit 18 entering near the upper end of conduit 14 and leaving near the lower end of conduit 14. Terminal. connections for the conduit 18 on the outside of the envelope 12 are provided respectively at 19 7o and 20; the heating agent making ingress and egress :therethrough.- A liquefied gas withdrawal conduit 21 is also provided leading from the lower part of the liquid container and here shown con-- necting to the lower end of the conduit 14 lead- 1; ing to the outside of envelope 12, and being provided with a stop valve 22 which controls the passage of liquid into extension 33. Disposed in the top of the vessel 11 is a conduit 23 terminating at its other end in cong0 nection 24 shown as disposed in the envelope 12 and provided with a closure plug 25. Disposed also in the top of the vessel 11 is a gas phase withdrawal conduit 26 which passes out through the outer envelope 12' and joins with a conduit a 27. Previous to the jointure with conduit 27, it is preferably provided with a stop valve 28 and a safety valve 29 which latter has a communicating conduit'30, shown as passing through the envelope 12. Such safety valve'insures the reno lease of any excess pressure that may occur therein. The conduit 27 is arranged to supply gas under pressure to ages receiver 34 for storage purposes; the conduit 26 is arranged to continue after its junction with conduit 27 as a conduit 31, which supplies consuming apparatus, the control of the supply being regulated by suitable means, for example a stop valve, as shown at 32.

It should be noted that the liquid holding vessel may have various shapes and forms and that it may be of a double walled construction, that is the inner liquid holding vessel may be formed of thin metal andbe disposed in spaced relatio within a heavy walled container.

The method of'using the apparatus described, according to the present invention is as follows: liquefied gas is introduced into the container through the filling conduit 23 and when the desired amount has been introduced, the filling line which is substantially atmospheric. The temperature of the walls of the container in contact with the liquefied gas is thereby reduced to substantially that of the liquefied gas. The pressure of the gas material that is subsequently delivered to the consuming apparatus through conduits 31 and 33 must be at a certain desired value, gen-. erally known in the art as a "pipe line pressure.

In order that gas material may fiow out of the container to the consuming apparatus, the pressure within the container must be increased to a value higher than pipe line pressure. Gas under pressure stored in the receiver 34 may be admitted to the newly charged container of liquefied gas by opening the valve 28. However, the quantity or the pressure of the gas thus stored is usually insuificient to effect the desired pressure increase.

Furthermore, when gas or liquid is withdrawn at a comparatively rapid rate, the pressure tends to drop. In this event, a further desired increase of pressure isobtained by circulating a heating fiuid, for example a portion of the previously vaporized and heated liquefied gas, through the conduit 18 whereby heat from the heating fluid is transferred to the liquid column in conduit 14, causing vaporization of a desired amount of the liquefied gas. The vapor, in flowing by the upper or inlet portion of conduit 18, may be superheatedto a small degree, after which it flows through conduit 15 into the gas space in vessel 11 above the main body of liquefied gas 10, thereby increasing the pressure therein and hence in all parts in open communication with the pressure vessel 11, including the storage receiver 34.

When the pressure in the liquefied gas container and in the receiver 34 has reached a value substantially in excess of the desiredpipe line pressure, the gas material will be in condition to fiow out into the consuming apparatus or pipe line. The outflow of liquefied gas is accomplished by opening valve 22 and the fiow occurs through connection 16 and conduit 21 and conduit 33 leading to the consuming apparatus. If the pressure in the containers should rise to a value greater than the desired excess over pipe line pressure, a reduction of pressure is eifected by opening valve 32 to permit gas to fiow out by means of conduit 31 to the consuming apparatus.

Repeated tests have shown that when the pressure within a container holding liquefied gas is increased by introducing gas above the surface of the liquid, the temperature of the main body of liquid does not rapidly rise to the temperature at which it would be in equilibrium with its vapor at the higher pressure existing after the introduction of the gas. On the contrary, it has been ascertained that heat transfer with consequent condensation of vapor at the quiescent surface of the liquefied gas occurs relatively very slowly.

It has also been observed, that, by reason of the efficient character of the insulation 13 and construction of the container, and the resulting slow rate of heat leakage into the body of liquefied gas in the container in which the specific heats of both the liquefied gas and of the materials of the container are important factors, the rise in temperature of the liquefied gas in the container is consequently very slow.

If, however, as in the auxiliary container 14,

with its vapor at the higher pressure before evaporation to produce the desired pressure increase occurs. a

It is usual to provide gas storage capacity in the form of the receivers shown at 34, to cooperate with the liquefied gas container or-cold converter" mainly for the purpose to be described. If, after the cold converter has been charged and pressure therein increased to the desired operating pressure sufiiciently above pipe line-pressure, as previously described, it isdesired completely to stop withdrawal of gasmaterial (as by closing valves 22 and-32), the liquefied gas 10 and the pressure container 11 being supercooled, that is, having a temperature whichv is below the temperature of equilibrium of liquefied gas with its vapor at the existing pressure, will have an appreciable capacity to absorb heat and will thus absorb an appreciable amount of the heat'that constantly leaks in before the temperature of equilibrium is reached and further evaporation of liquefied gas can occur. Therefore, the rate .of pressure rise within the liquefied gas c'ontainer and its connected storage receivers will be substantially reduced, as compared to the rate that would occur if the liquefied gas temperature had been brought up to the temperature of equilibrium at the desired working pressure immediately after charging, as occurs with the former method of vaporizing a portion of the liquefied gas in which the heatis applied to the main body of liquefied gas.

It will be" seen, therefore, that with a given capacity of storage container, the elapsed period of time from complete stoppage of withdrawal until the pressure has reached a value sufficiently high to cause the safety pop valve to open and release gas material to the atmosphere, is substantially increased by the method and apparatus of the invention.

Since certain changes in carrying out the above process and in the constructions set forth, which embody the invention may be made without departing from its scope, it is intended that all matter'contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. The method of dispensing gas material from a container for liquefied gases, having a main inner vessel, an insulating envelope and an auxiliary vessel in said envelope in free communication at all times with said main vessel at points both above and below the normal liquid level thereof, which comprises charging said container with a quantity of gas in the liquid phase under atmospheric conditions, closing the sameto the atmosphere, passing a heating agent in heat-ex changing relation with the portion of liquidin said auxiliary vessel at a rate sufiicient to maintainby vaporization a pressure in the main vessel greater than that of the pipe lines, irrespective of the rate of discharge from said container, and

with at points both above and below the normal liquid level therein, and a heating element adjacent said auxiliary vessel arranged to heat the liquid column within the same.

3. In apparatus for dispensing gas material, the combination with a container for liquefied gas having a main inner vessel and an insulating envelope therefor, of an auxiliary vessel disposed in said insulating material adjacent said inner vessel and communicating therewith at a point near the top thereof and also at a point near the bottom thereof, and a heating conduit disposed within said auxiliary vessel and provided with connections leading to the exterior of said container through which a heating agent is supplied.

4. In apparatus for dispensing gas material, the combination with a container for liquefied gas having a main inner vessel and an insulating envelope therefor, of an auxiliary vessel disposed in said insulating material adjacent said inner vessel and communicating therewith at a point near the top thereof and also at a point near the bottom thereof, and a conduit disposed longitudinally within said auxiliary vessel and provided with inlet and outlet connections leading to the exterior of said insulating envelope.

'5. In apparatus for dispensing gas material, the combination with a container for liquefied gas having a main inner vessel and an insulating envelope therefor, of a relatively large conduit disposed in said insulating envelope partially surrounding said inner vessel and connected in constant open communication with said inner vessel at points both above and below the normal liquid level therein, and a relatively small conduit for the passage of a heating agent disposed within substantially the greater portion of said relatively large conduit.

6. In apparatus for dispensing gas material, the combination with a container for liquefied gas having a main inner vessel and an insulating envelope therefor, of a relatively large conduit disposed in said insulating envelope partially surrounding said inner vessel and having a reduced upper end in constant communication with said inner vessel at a point above the normal liquid level thereof and a prolonged lower end in constant communication with said inner vessel at a point substantially at the bottom thereof, a liquid phase withdrawal connection leading from said prolonged lower end and to a point on the exterior of said insulating envelope, an independent'gas'phase withdrawal connection leading from the gas space of said vessel to a point on the exterior of said insulating envelope, and a relatively small conduit for the passage of a heating agent disposed within substantially the greater, portion of said relatively large conduit.

LEO I. DANA. 

